Control of gloss in printing



April 22, 1947. H c. FISHER ,4

CONTROL OF GLOSS IN PRINTING I Filed Aug. 8, 1941 CALENDER INVENTOR.fl/14 C HSHEQ.

ATTORNEYS.

Patented Apr. 22, 1947 Q coN'raoL F GLOSS IN rnmrmc Harry G. Fisher,Cincinnati, Ohio, assignor, by mesne assignments, to Consolidated WaterPower & Paper Company, Wisconsin Rapids, Wis., a corporation ofWisconsin Application August 8, 1941, Serial No. 406,073

My invention relates to processes whereby thenature of the surface ofprinting inks upon paper and paper board can be controlled for gloss inthe final effect.

Irrespective of the smoothness of the finish of a piece of paper boardor paper, it has been found practical by me, by certain sizingtreatments in connection with the practice of coating the board, tocontrol the gloss in printing to the end that a dull or mat surface canbe provided, which is at the same time as smooth as practical. Thus, asurface which to all external appearance is one which will take a highgloss, smooth print-.

ing, can be made to be such that the printing will have a velvet or matsurface. The control is particularly valuable Where a color coating richin binder is used to insure a high wax pick test.

The control-is applied previous to the coating step, by which I refer tothe application of coat- -ings such as those in an aqueous vehiclecontaining finely divided mineral matter, such as clay and suitablebinder substances, generally referred to as color coatings.

I have discovered that if application is made to the fibrous web,particularly where it is freshly made and moving continuously from a,paper or paper board machine, of a substance which is a penetrating Orwetting agent, then, following a color coating, drying and calendering,the surface of the coated fibrous web will be wettable or penetrable incontrolled-degree to the vehicle of printing inks, thus leaving on thesurface of the web a non-glossy final surface of dried ink.

film, as distinguished from a glossy final surface.

To illustrate an optional practice I have, in the appended drawings,shown a diagram of a practice applied to paper board whereby it may becolor coated, dried and calendered prior to printing. In this diagramthe web of paper board 2, is shown as coming from the final drying rollsl of a paper machine, after which it passes to the breaker stack orpreliminary calendering operation comprising stack of rolls 3. From thebreaker'stack which is equipp d With boxes 4, 4a, whereby the sizingemployed by me in my practice is applied, the web may pass to a colorcoating apparatus which, as shown, consists of rolls 5, to which colorcoating is applied by means of applicator rolls 6 in a controlledamount.

Color will be drawn from a suitable fountain! and applied to theapplicator rolls. The coating actic thus pursued wherein a film isestablished on a roll by an applicator roll and this film thentransferred to a paper web brought into contact with the film,necessitates a heavy slurry 12' Claims. (01. 117-60) of pigment andbinder and a thin film. In the claims that follow this mode of coatingis referred to as printing. From the color coater the web may passthrough drying and calendering equipment as indicated by boxes in thediagram suitably labeled to show purpose and relative location.

The substances which I have found to impart the penetrating quality orwetting quality when.

applied to the board before color coating, which quality continues aftercolor coating, drying and calendering, ar generally penetrating orwetting agents, preferably of organic type such as butyl carbitol, themonobutyl ether of diethylene glycol, which is a, colorless andpractically odorless liquid. Also, the sodium salts of sulphuric acidesters of the higher fatty alcohols are useful as penetrants, as well asothers of the wide group of wetting agents similar in behavior to thealkyl sulphate or sulphonate materials, including, for example, thesodium salt of an alkyl naphthalene sulfonic acid. I do not limit myselfto these particular wetting or penetrating agents, however.

Referring to the butyl carbitol, the amount used is not critical, andflat printing effects without gloss have been obtained with quantitiesvarying from a few percent up by volume in the sizing applied in thebreaker stack or previous thereto, whether this be starch or other size.

For example, in a companion applicationto the present one, Serial No.412,831, filed September 29, 1941 now replaced with a continuationapplication Serial No. 501,320 filed September 4, 1943, I have discloseda practice for preparing paper board or paper for color coating, whichconsists in the application of substances which are plasticizable, andyet water soluble, and

'which are applied to the boardat or ahead 'of the breaker stack ofcalenders to give it a surface size of adherent character. Thepenetrants or wetting agents can be added to the sizing substances ofthis process in quantities which will not break down the plasticizablenature thereof too far, with the result of permitting the very smoothfinish and firm adhesion which is accomplished upon coatings andcalendering as disclosed in said companion application, and yetpromoting flatness in finish of printing upon the color coating.Alternatively, the penetrants or wetting agents can be applied to theboard from solution or dispersion separate from that of the sizingsubstances.

. In one practice I have used on the breaker stack of calendersa fivepercent polyvinyl alcohol (PVA) size in water to five volumes of which II have added one volume of butyl carbitol, the whole being kept hotduring use. The application may be made by the breaker stack calenderboxes as already noted or prior thereto. It is desirable, however, toapply the penetrating agent as close to the point of color coating aspossible, but prior thereto, so that it does not dry too much beforecoming into contact with the wet color coating mixture. The barrier toready wetting of the fibres of the paper board which is interposed by aplasticized layer of PVA, can be controlled, I have found, by the use ofthe penetrating agent, and in this way, the finish in printing withappropriate inks upon a board sized with the PVA and then color coatedand calendered can'be controlled. In my opinion the result is due tofacilitating the wetting of this barrier by the wet color coating due tothe presence of the agent that facilitates wetting and to some degree ofabsorption of wetting agent and PVA into the color coating itself, thuschanging the nature of the finished, dried, and calendered color coatingand, in turn, its resistance to absorption of printing ink. Too much ofthe wetting or penetrating agent will destroy the plasticizable natureof the PVA. The wetting or penetrating agentshould be water soluble orcompatible with any sizing or plastic agent with which it is employed,for practical reasons.

My invention applies to the use of starch size in the breaker stack orprior thereto (for example, in a size press in the drier section of thepaper machine), 'or any other water soluble or dispersible surface sizewith or without a plastic agent which is also water soluble ordispersible.

In a typical practice using starch size in the breaker stack, I havemixed five volumes of starch solution of six percent concentration oflow viscosity starch, by weight, with one volume of butyl carbitol. Thehot mixture was applied to the surface of the paper board bymeans of thebreaker stack calender boxes as already described, following which thecolor coatingwas applied, dried and calendered. When later printed withink, the fullest in non-glossy characteristics of the ink was realized.

In still another practice, the penetrating agent, butyl carbitol, wasadded to a water solution containing both a plastic agent and starch. To

- four volumes of starch solutioncontaining six per cent low viscosityconverted starch, by weight, were added one volume of polyvinyl alcoholof five per cent concentration in water, by weight, and to the hotmixture of 'these was added one volume of butyl carbitoLthe completedmixture being kept hot, and being applied to the paper board by calenderbox of the breaker stack of calenders. Following this the color coatingwas applied to the treated surface of the sheet, and was dried andcalendered. Later the coated sheet was printed to develop the maximum innonglossy characteristics of the ink.

Instead of mixing the wetting or penetrating agent into the sizingsolution it can be applied to the'sheet of board as a separate solutionfrom a means of application, either on the breaker calender stack orprior thereto as in a size tub. Thus, in the appended drawing thesolution of plastic material, alone or in admixture with other sizingmaterial such as starch, can be applied to one side of the sheet ofboard in breaker calender box I, following which the solution of wettingor penetrating agent is applied in calen- 4 ing operation, its dryingand calendering of the coated sheet. Conversely, the wetting orpenetrating agent can be applied to the board ahead of the plastic orsizing material as in box 4,

followed by the plastic or sizing material in box 4a, in which event thefullest in film-forming characteristics of the plastic or sizingmaterial will not be developed because absorption of them into thesurface of the sheet rather than retention on the surface will bepromoted. However, for some purposes, as when the body of a sheet mayhave to be made highly resistant to penetration of solution, a surfacetreatment with penetrating or wetting agent before plastic or surfacesizing material will prove advantageous. A similar treatment can beafforded the other side of the sheet. Where the wetting or penetratingagent is applied separately, it can be used in concentrated or dilutedform as necessitated by the effect desired on the printed color coatedsheet. I have used the liquid penetrating agent, butyl carbitol, in itsconcentrated form and also in dilution with water. A dilutionof threevolumes water to one of butyl carbitol is effective, but I do not limitmyself to such proportions,

In a typical practice of the invention, the sheet of paper board 2coming from the final drying rolls l of the paper machine passes to andthrough the nips of calender rolls in the breaker stack 3. From calenderbox 4 of the breaker stack a water solution of plastic material andstarch, as described above, was applied by nip pressure to the topsurface of the paper board web. Immediately below on the breaker stack,in calender box 4a, the solution of wetting or penetrating agent wasapplied to the top surface of the board by nip pressure over thetreatment of plastic material and starch. Since the time consumed by thesheet of board in passing from the calender nip at 4 to the one at 4a.is so short, a matter of a fraction of a second, the treating materialapplied by 4 is not dry by the time the treatment by do occurs, hencethere is in reality amixing effect of one treating material upon theother resulting ina surface treatment of paper board especially suitedfor the reception of color coating to be dried and calendered, and thenprinted to produce the desired result of fiat or mat surfaced printing.

I have employed letter press printing in my process, the ink of whichcomprises pigments dispersed in linseed varnish along with the usual 00-balt or similar drier. and with a small admixture of wax such asceresine to help prevent offset and enhance penetration. When printedupon paper or board such inks set to a slight degree by penetration intothe surface upon which they are printed, but mostly by oxidation andpolymerization of the vehicle. For extremely fiat printed effects thevehicle will comprise a preponderance of soft linseed varnishes, whereasfor more glossy printed results the vehicle will contain harder linseedvarnishes, many times in admixture with resinous materials. Since fiatprinted effects are desired in the printed coated board of my invention,I naturally prefer to use inks formulated with that purpose in mind.However, it is not always possible to use the softest of inks when fiatprinted results are desired because of adjustments necessary on theprinting press and relationships between various colors and kinds ofinks. This, then, makes my process particularly cause variations in inkformula can be made to der box in followed, inturn, by the colorcoatprovide for necessary requirements in it, while reliance is made onthe treatment underlying the color coating to insure the fiat printedresult.

The penetrating agent does not affect deleteriously the adherence of thecolor coating although there is an enhanced penetration of the vehicleof the coating. Apparently this enhanced penetration of vehicle of thecoating in turn increases the ability of the dried and calendered colorcoating to absorb ink vehicle to produce a fiat printed effect. Theprecise reason why the fiat printed effect occurs is not obvious norpredictable from the nature of the material used.

The discovery that this effect does in fact follow is the essence of myinvention.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent is:

1. The process for producing a coated surface on paper webs which willgive a mat imprint when subsequently printed with non-aqueous base inks,which consists in applying a water wetting and penetrating agent to thesurface of the web and then coating the web by printing it with amineral coating in an aqueous vehicle and then drying the said coating.

2. The process for producing a coated surface on paper webs which willgive a matimprint when subsequently printed with non-aqueous base inks,which consists in applying a water wetting and penetrating agent to thesurface of the web and then coating the web by printing it with amineral coating in an aqueous vehicle and then drying the said coating,said wetting and penetrating agent being an organic water a solublecompound.

3. The process for producing a coated surface on paper webs which willgive a mat imprint when subsequently printed with non-aqueous base inks,which consists in applying a water wetting and penetrating agent to thesurface'of the web and thencoating the web by printing it with a mineralcoating in an aqueous vehicle and then drying the said coating, saidwetting and penetrating agent being butyl carbitol.

4. The process for producing a coated surface on paper webs which willgive a mat imprint when subsequently printed with non-aqueous base inks,which consists in applying a water wetting and penetrating agent to thesurface of the web and then coating the web by printing it with amineral coating in an aqueous vehicle and then drying the said coating,said wetting and penetrating agent being an organic watersolublecompound of sulfated or sulfonated higher carbon chain fattyacids.

, '6 5. The process for producing a coated surface on paper webs whichwill give a mat imprint when subsequently printed with non-aqueous baseinks, which consists in applying a water wetting and penetrating agentto the surface of the web and then coating the web by printing it with amineral coating in an aqueous vehicle and the drying the said coating,said wetting and penetrating agent being a salt of alkyl naphthalenesulfonic. acid.

6. The process for producing a coated surface on paper webs which willgive a mat imprint when subsequently printed with non-aqueous base inks,

which consists in applying to the'web a film of a plasticizable watersoluble compound and a we.-

ter wetting and penetrating agent, then smoothing and compacting thesurface of the web, then coating the smoothed and compacted surface byprinting it-with mineral coat and finally drying and calendering theweb.

7. The process of claim 6 in which the proportion of wetting andpenetrating agent is not sufficient to render ineflectual theplasticizing property of the said plasticizable compound.

10 8. The process for producing a coated surface on paper webs whichwill give a mat imprint when subsequently printed with non-aqueous baseinks, which consists in applying a water wetting and penetrating agentto the surface of the web and then coating the web by printing it withamineral coating in an aqueous vehicle, the paper web when the wettingand penetrating agent is applied being freshly made and then drying thecoating.

9. The process for producing a coated surface web and then coating theweb by printing it with a mineral coating in an aqueous vehicle anddrying the said coating, the said wetting and penetrating agent beingapplied to freshly made paper in the breaker stack of calenders.

10. The process for producing a coated surface on paper webs which willgive a mat imprint when subsequently printed with non-aqueous base inks.which consists in applying a water wetting and penetrating agent to thesurface of the web and then coating the web by printing it with amineralcoating in an aqueous vehicle, the mineral coat being appliedimmediately as a continuous step after applying the penetrating agentand then dried and the web calendered.

49 11. The process of claim 9 in which the minplied immediately as acontinuous step after the smoothing and compacting step.

- HARRY C. FISHER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name 4 Date 5 1,777,459 Baddiley Oct. 7,1930 1,995,623 Richter Mar. 26, 1935 2,240,031 Bour Apr. 29, 19412,214,565 -Montgomery Sept. 10, 1940 1,838,358 Bradner Dec. 29, 19312,005,397 Schur June 18, 1935 2,256,853 Schwartz Sept. 23, 19412,316,120 McLaurin Apr. 8, 1943 2,108,806 Finzel Feb. 22, 1938 2,045,517Bruson June 23, 1936 05 2,105,982 Massey Jan. .18, 1938 2,251,296 ShippAug. 5. 1941 ,7 Q, FOREIGN PATENTS j Number W Country Date British Dec.31, 1928

